A work machine such as an agricultural tractor may be driven with motive force taking several different forms, such as a rear wheel drive, four wheel drive (4WD), mechanical front wheel drive (MFWD), track-type drive, etc. In the case of an MFWD equipped tractor, the front wheel drive typically is not full time, and an electronic switch in the operator's station is used to switch between rear wheel drive and MFWD mode.
An MFWD tractor may include an internal combustion (IC) engine which provides input power to a transmission, which in turn is coupled with and drives the rear axles through a rear end differential. The transmission may also include an output shaft, typically facing in the forward direction, which connects via a drive shaft or the like with the MFWD at the front end of the tractor. The drive shaft output from the transmission may be clutched to selectively provide output power from the transmission to the MFWD. Conventional clutch designs are effective for engagement and disengagement of the drive shaft, but tend to be relatively complex in design.
An example of a clutch arrangement used in an MFWD equipped tractor is disclosed in U.S. Pat. No. 6,364,045, which is presently purchased by the assignee of the present invention for use in the John Deere 5000 series tractors. Referring to FIG. 2, a cylinder 55 is interposed between a clutch member 52 and a drive gear 37. The cylinder 55 includes a generally U-shaped cutout in which a piston 57 is slidably positioned. Hydraulic pressure is transmitted through the shaft 36, then at a 45 degree angle through the back wall of cylinder 55, before finally acting on piston 57. The number of components and component configuration adds to the complexity and cost of the clutch design.
What is needed in the art is a clutch for a gear arrangement in a transmission which is simple, economical and reliable.